The present invention relates generally to the field of producing fragment-free openings with the use of explosive materials and more specifically an apparatus and method for creating openings in housings for improvised explosive devices (IEDs) without setting off the IED.
Very frequently, IEDs are placed in hardened enclosures, such as steel drums, ammo boxes, or the like. This occurs because the perpetrator wants to make it difficult or impossible for the bomb to be disarmed before it detonates. Frequently, these enclosures are booby-trapped so that if their lids are pried off, the IED will explode.
Various techniques have been in place in the field of Explosive Ordinance Disposal (EOD) for creating openings in the hardened container of the IED as a first step in disablement. Typically, linear-shaped charges are used to create such openings. These shaped charges consist of a chevron-shape metallic casing, which is usually copper, aluminum or lead, that contains a set quantity of high explosives, such as RDX or PETN (pentaerythritoltetranitrate). The linear-shaped charge cuts the metal casing by accelerating the metal envelope in the wedged (or chevron-shaped) portion of the charge into each other, thus creating a high-velocity metallic jet. This metallic jet is capable of penetrating or cutting steel and other hardened targets. The linear-shaped charges can also send fragments into the target and to the surroundings. Other high-explosive charges that have no metal case that are employed in direct contact with the surface of a metallic target generally produce fragments by inducing multiple stress transients into the target, resulting in spallation of the back of the target.
In essence, spallation occurs when a typical high-explosive charge is detonated in contact with a hardened target, such as a steel plate. As a result, the charge can cut, punch or tear a hole in the steel plate directly underneath the charge. The cutting or punching process is due to the high-intensity shocks generated by the explosive charge. These high-intensity shocks compress and put in tension the steel in nanosecond to microsecond time frames. If strong enough, the pressure generated from the shock perturbations in the steel can overcome the critical fracture stress level in the steel so that steel will fracture. When explosively generated shocks travel through the steel, it compresses the steel. When this compressive wave reaches a free boundary (i.e., air) having a lower shock impedance than steel, to conserve momentum, part of the shock will reflect back into the steel, placing the steel into tension. Tension waves generated from high-intensity shocks can cause the steel to be pulled apart in a laminar fashion from the free surface opposite the explosive charge. The process of steel being separated in this laminar-like fashion is called "spallation." The spalling process produces secondary fragments from the main piece of steel that is under explosive attack.
In contact operations for explosively cutting steel, generally a main piece of steel is cut from the surface that can travel at high velocities along with the pieces that have spalled from the main piece of steel, resulting in high-energy, high-velocity fragments. In EOD operations, the impact of fragments can initiate the target explosives. Therefore, the generation of fragments is undesirable. In Special Weapons and Tactics-type (SWAT) operations, explosively generated fragments can injure or kill personnel; therefore, a high-explosive charge capable of generating no fragments is highly desirable.
In the art of bomb disablement, most terrorist-type bombs are defused remotely by a disrupter. A disrupter is a tool designed to fire remotely a variety of projectiles into a terrorist-type bomb to disable/dislodge the circuit or other bomb components. The most common projectile is water; however, in order to penetrate steel containers containing sensitive explosives without shock-initiating the explosives, water alone is not a suitable candidate. Thus, one of the objectives of the present invention, when an IED is enclosed in a steel or other hardened container, is to be able to create a fragment-free portal through the steel container without setting off the IED. This fragment-free hole can be made in microseconds prior to water from a disrupter arriving at the target interface. Thus, the tandem capability offers a new level of advanced capabilities in the art of bomb disablement.
The present invention can be used to disable bombs, ordnance, for explosive entry for hostage rescue, and in industrial applications for explosive diaphragms for venting hazardous containers or other extreme environments. The present invention has the ability to create a cruciform-shaped cut or slit in a steel target and subsequently peel back the steel, thus creating a generally large, symmetrically shaped square or rectangular hole in a steel target and is generally referred to as "Magic Cube.TM." by the inventor. This hole is produced with a greatly reduced shock pressure induced inside the metal container where the target is located.
Thus, among the advantages of the present invention are to be able to use controlled explosive charge that produces a fragment-free hole in a hardened target. Another advantage of the present invention is to create the apparatus from readily available materials. The present invention can be used alone, in tandem, or in multiple combinations with other disablement projectiles in the field of EOD. Another advantage of the invention is to use an explosive charge with controlled shock pressures which can be detonated on the surface of a hardened target or container containing sensitive explosives (i.e., nitroglycerin/nitroglycol-based dynamites, and/or lead azide-based detonators) that are positioned only inches away from the charge without initiating any of the sensitive explosives. Another advantage of the invention is to provide an apparatus that, by design, can absorb the fragments generated by a detonator and produce no fragments into the target. This allows the charge to be fired in close proximity to personnel for military or police operations and in the field of special effects for the motion picture industry. Yet another objective of the present invention is to be able to allow personnel in SWAT teams and military hostage extrication teams to use the apparatus and method to create controlled explosive entry. These types of teams, whether military or civilian, can also use the apparatus of the present invention to produce viewing ports and gun portals in dealing with hostage situations.
Yet another advantage of the present invention is to provide the ability to produce instantaneous low-pressure, fragment-free holes through steel bulkheads and damaged buildings or ships or to allow urban rescue personnel to gain access for placing oxygen or air hoses, lighting or microphones for persons trapped on the other side of a bulkhead. Another application of the present invention is to use the present invention on a flat, steel plate or a domed surface which can serve as an economical explosive fragment-free explosive diaphragm that could be used in industrial hazardous environments for mixing or venting of materials in tanks. Yet another objective of the present invention is to be able to configure the apparatus in different sizes and configurations to create entry holes of different sizes on targets having a variety of thicknesses and constructed from a variety of materials. Yet a further objective of the invention is to be able to deliver the apparatus manually or robotically and to be able to easily affix the apparatus to a target having surfaces which may be curved or wet to create portals therein.
Yet another advantage of the present invention is to successfully penetrate a variety of hardened targets, such as, for example, steel targets having a thickness of 0.035-0.125" which contain a nitroglycerin-based dynamite as close as 2" from behind the target interface without initiating the dynamite. Yet another objective is to produce portals or openings as large as 9" in diameter in steel enclosures as thick as 0.25". Yet another objective of the present invention is to produce fragment-free holes in metallic targets that are very large as compared to the surface area of the charge. Thus, depending on the loading vs. the steel target thickness, the apparatus can produce holes in steel targets ranging in size from the charge's surface area to greater than 8 times the charge's surface area.
How the present apparatus and method are accomplished can be more readily understood by those skilled in the art from a review of the description of the preferred embodiment that appears below.